1. Field to the Invention
This invention relates to drawing apparatus intended in particular--but not exclusively--for the preparation of technical drawings, such as engineering drawings and the like.
2. Description of the Prior Art
There is a wide variety of drawing equipment available for use in the preparation of technical drawings, to achieve a high standard of accuracy, for obtaining and communicating technical information. Drawing boards are well known devices used in the production of engineering drawings and graphic artwork. Such boards are often used in conjunction with a variety of drawings instruments, and notably 45.degree. and 30.degree.-60.degree. set squares, as well as adjustable set squares, in producing such drawings.
All commercially-available drawing boards provide a flat surface on which the working paper may be laid; many drawing boards also incorporate special means allowing the firm attachment of the paper to that flat surface, though this may often be performed with self-adhesive tape. Most commercially-available boards also allow for adjustment of the working angle of the flat surface by means of a mechanism associated with the board, below the drawing surface. Also, many commercial boards include a so-called parallel motion device which enables a horizontal line to be drawn at any place on a piece of paper supported on the flat surface. When the parallel motion device is used in conjunction with an adjustable set square, parallel lines at any angle to the horizontal may be drawn at any place on the paper.
Many commercial drawing boards are in the form of a free standing unit which may comprise a desk, or more simply just a frame, on which is supported the drawing board proper. Such a free standing unit is not easily portable and is relatively bulky. If it is likely that several people will wish to use a number of such boards at the same time, then a specialised room must be devoted to that purpose.
Other commercial drawing boards are portable devices which are intended to be placed on a flat working surface, but which may be propped to lie at some convenient angle to the working surface. Such a board may be relatively simple - and at its simplest may be little more than a rectangular piece of wood of a suitable thickness. If such a drawing board incorporates means for adjusting the working angle of the drawing surface, that usually comprises a mechanical prop arrangement attached to the underside of the board. The prop arrangement is then prone to damage when handled roughly, and makes the drawing board more awkward to transport and to store.